How to read data from nested array in Firestore

I have the below structure in my Firestore and I want to read data and store it in ArrayList like I have “amountArrayList” which will read data from the “transactions” field in Firestore, I want to read all the “amount” fields from “transactions” field and make array list of it so that I can show it in list manner.

My code

Map<String, Object> map = document.getData();
for (Map.Entry<String, Object> entry : map.entrySet()) {
    if (entry.getKey().equals("transactions")) {
        System.out.println(entry.getValue().toString());
    }
}

Output

[{transactionType=Credit, amount=3000, dateToStr=17/12/2021, timeToStr=08:06:10, description=}, {transactionType=Credit, amount=2000, dateToStr=17/12/2021, timeToStr=08:06:50, description=}]

Answer

Since transactions is an array field, the value you get from entry.getValue() is a List of objects. Since each of these objects in the JSON has properties, they each will be a Map<String, Object> again in the Java code.

A simple way to print the amounts would be something like:

List transactions = document.get("transactions");
for (Object transaction: transactions) {
  Map values = (Map)transaction;
  System.out.println(values.get("amount")
}